Charge pumps are used to provide boosted voltages above the power supply voltage in electronic circuits. Today's mobile electronic products require low power consumption and fast startup times. For charge pump circuits this means that they need the desired boosted pump voltage quickly, and once stable consume as little power, or current, as possible. A conventional charge pump control circuit generates a high frequency and low frequency oscillator and uses circuitry to control the clock switching. During startup, the high frequency clock is used to generate the desired high output voltage at which point, the low frequency clock will take over the pump operation. The main disadvantage of using this approach is in order to maintain the minimum positive pump voltage, the frequency of the low frequency oscillator must be increased which increases operating power consumption. One solution is to add filter capacitance to the output which will keep the charge longer; however, this will contribute to a much longer startup time.
Thus there exists a need for a fast startup charge pump control system that consumes as little power during operation as possible.